The formula is p to the nth power (pn) < 0.01.Originally Posted by Gerardo
p = probability of not getting what you want from a single egg
n = number of eggs
Here's the easy way to calculate the formula. Using the calculator in Windows' Accessories folder, choose view --> scientific. Then enter the value of p, press the xy key, enter a value for n, and hit the <ENTER> key.
Example 1: You have a normal looking ball python that could be heterozygous albino. You mate it to an albino ball python. You want albinos, and you do not want normal looking babies. The probability of getting an albino is 0.5, and the probability of getting a normal looking baby (p) is 0.5.
Multiply 0.5 by 0.5 for as many times as it takes to get a number less than 0.01.
In this case, 0.5 * 0.5 * 0.5 * 0.5 * 0.5 * 0.5 * 0.5 (or 0.5 to the seventh power) = 0.008 (rounded). In other words, seven normal looking snakes and no albino snakes has less than a 0.01 probability of occurring by chance.
Example 2: You have a normal looking ball python that could be heterozygous albino. You mate it to a normal looking, het albino ball python. You want albinos, and you do not want normal looking babies. The probability of getting an albino is 0.25, and the probability of getting a normal looking baby (p) is 0.75.
Multiply 0.75 by 0.75 for as many times as it takes to get a number less than 0.01. In this case, 0.75 to the seventeenth power = 0.008 (rounded). In other words, seventeen normal looking snakes and no albino snakes has less than a 0.01 probability of occurring by chance.
The above assumes that albinos and nonalbinos have an equal chance of hatching. This is not always true. Or you may have plain bad luck. But it is the place to start, and almost all of the time it will give the right answer.
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